Method of controlling chemical concentration in electrolyte and semiconductor apparatus

ABSTRACT

A method of controlling chemical concentration in electrolyte includes measuring a chemical concentration in an electrolyte, wherein the electrolyte is contained in a tank; and increasing a vapor flux through an exhaust pipe connected to the tank when the measured chemical concentration is lower than a control lower limit value.

PRIORITY CLAIM AND CROSS-REFERENCE

This application claims priority to U.S. Provisional Application Ser.No. 62/660,154, filed on Apr. 19, 2018, which is herein incorporated byreference in its entirety.

BACKGROUND

Conductive interconnections on integrated circuits typically take theform of trenches and vias in the background art. In modern deepsubmicron integrated circuits, the trenches and vias are typicallyformed by a damascene or dual damascene process. Copper is currentlyused in ultra large scale integration (ULSI) metallization as areplacement for aluminum due to its lower resistivity and betterelectromigration resistance. Electrochemical copper deposition (ECD) hasbeen adopted as the standard damascene or dual damascene process becauseof larger grain size (good electromigration) and higher depositionrates. More particularly, electrochemical plating (ECP) is well suitedfor the formation of small embedded damascene feature metallization dueto its ability to readily control growth of the electroplated film forbottom-up filling, and the superior electrical conductivitycharacteristics of the electroplated film.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a flowchart of a method of controlling a chemicalconcentration in an electrolyte in accordance with some embodiments ofthe present disclosure;

FIG. 2 is a block diagram of a semiconductor apparatus in accordancewith some embodiments of the present disclosure;

FIG. 3A is a top view of a semiconductor apparatus and an exhaustassembly of FIG. 2;

FIG. 3B is a schematic view of a wafer in an electroplating cell of FIG.3A during an ECP process;

FIG. 3C is a schematic view of the wafer in the electroplating cell ofFIG. 3B during a rinsing process;

FIG. 4 is a concentration-time relationship chart presented by an faultdetection and classification (FDC) server of FIG. 2;

FIG. 5 is a perspective view of the exhaust assembly and a tank of FIG.3A, in which the exhaust assembly is in a closed state;

FIG. 6 is a perspective view of the exhaust assembly of FIG. 5;

FIG. 7 is a perspective view of the exhaust assembly and the tank ofFIG. 3A, in which the exhaust assembly is in an open state;

FIG. 8 is a perspective view of the exhaust assembly of FIG. 7;

FIG. 9 is a perspective view of the exhaust assembly and the tank ofFIG. 3A, in which the exhaust assembly is in a partially-open state;

FIG. 10 is a perspective view of the exhaust assembly of FIG. 9; and

FIG. 11 is a perspective view of an exhaust assembly and a tank inaccordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

FIG. 1 is a flowchart of a method of controlling a chemicalconcentration in an electrolyte in accordance with some embodiments ofthe present disclosure. The method begins with block 10 in which anexhaust assembly sends a volume flow rate of an exhaust pipe to acomputer integrated manufacturing (CIM) system. The method continueswith block 20 in which a prober measures a chemical concentration in theelectrolyte. The method continues with block 30 in which an analyzerreceives the measured chemical concentration from the prober. The methodcontinues with block 40 in which a fault detection and classification(FDC) server receives the measured chemical concentration from theanalyzer to form a concentration-time relationship chart. The methodcontinues with block 50 in which the FDC server sends the measuredchemical concentration to the CIM system. The method continues withblock 60 in which the exhaust assembly controls an opening area of theexhaust pipe based on the volume flow rate of the exhaust pipe and themeasured chemical concentration. While the method is illustrated anddescribed below as a series of acts or events, it will be appreciatedthat the illustrated ordering of such acts or events are not to beinterpreted in a limiting sense. For example, some acts may occur indifferent orders and/or concurrently with other acts or events apartfrom those illustrated and/or described herein. In addition, not allillustrated acts may be required to implement one or more aspects orembodiments of the description herein. Further, one or more of the actsdepicted herein may be carried out in one or more separate acts and/orphases.

FIG. 2 is a block diagram of a manufacturing system 200 in accordancewith some embodiments of the present disclosure. The manufacturingsystem 200 includes the exhaust assembly 110, the semiconductorapparatus 120, the CIM system 130, the prober 140, the analyzer 150, andthe FDC server 160. The exhaust assembly 110, the semiconductorapparatus 120, and the FDC server 160 are electrically connected to theCIM system 130. The semiconductor apparatus 120 is electricallyconnected to the exhaust assembly 110. The analyzer 150 is electricallyconnected to the prober 140. The FDC server 160 is electricallyconnected to the analyzer 150. In some embodiments, the analyzer 150 isa real-time analyzer (RTA). The FDC server 160 may include a dataprocessor mechanism configured to process real-time data from theanalyzer 150.

FIG. 3A is a top view of the semiconductor apparatus 120 and the exhaustassembly 110 of FIG. 2. The semiconductor apparatus 120 may be a clustertool that has the capability to sequentially process substrates (e.g.,semiconductor wafers W) in a controlled processing environment. Thesemiconductor apparatus 120 includes the exhaust pipe 122, a tank 124,and a controller C. The tank 124 contains a solution S therein, and aportion of the prober 140 of FIG. 2 is in the tank 124 to measure achemical concentration in the solution S. The solution S is anelectrolyte. In some embodiments, the electrolyte S includes water(H₂O), copper sulphate (CuSO₄), hydrochloric acid (HCl), sulfuric acid(H₂SO₄), and chemical additives, such as an accelerator (e.g.,mercapto), a suppressor (e.g., polyethylene glycol (PEG)), a leveler(e.g., quaternary nitrogen), or the like. The exhaust pipe 122 isconnected to the tank 124 and has an opening O above the electrolyte S.The opening O is at an end of the exhaust pipe 122 proximal to the tank124. In the tank 124, vapor including water and crystalline acids mayexist in an upper space of the tank 124 that is not occupied by theelectrolyte S. The controller C is electrically connected to the exhaustassembly 110, and is configured to control the exhaust assembly 110based on the measured chemical concentration. For example, when themeasured chemical concentration is lower than a control lower limitvalue, the vapor flux through the exhaust pipe 122 is increased. Whenthe measured chemical concentration is higher than a control upper limitvalue, the vapor flux through the exhaust pipe 122 is decreased.

Reference is made to FIGS. 2 and 3A. When the manufacturing system 200of FIG. 2 is in operation, the exhaust assembly 110 sends a volume flowrate of the exhaust pipe 122 to the CIM system 130, and the prober 140measures the chemical concentration in the electrolyte S. The analyzer150 receives the measured chemical concentration from the prober 140.Thereafter, the FDC server 160 receives the measured chemicalconcentration from the analyzer 150 to form a concentration-timerelationship chart, and sends the measured chemical concentration to theCIM system 130. The CIM system 130 determines an exhausting parametervalue based on the volume flow rate of the exhaust pipe 122 and themeasured chemical concentration through computation. The CIM system 130combines the exhausting parameter value and a process recipe and sendsthem to the semiconductor apparatus 120 to control the exhaust assembly110 based on the exhausting parameter value and the process recipe. Insome embodiments, the exhausting parameter value includes the openingarea of the exhaust pipe 122. For example, if the measured chemicalconcentration (e.g., copper concentration) is too low, the opening areaof the exhaust pipe 122 is increased by the exhaust assembly 110 toincrease the rate of piping the vapor out of the tank 124 and to lowerthe pressure in the tank 124. As a result, the speed of solventevaporation from the electrolyte S is accelerated, such that thechemical concentration in the electrolyte S increases. On the otherhand, if the measured chemical concentration is high enough or too high,the opening area of the exhaust pipe 122 is decreased by the exhaustassembly 110 to retain the vapor in the tank 124. As a result, thechemical concentration in the electrolyte S will not continuouslyincrease for the reason of solvent evaporation from the electrolyte S.

The exhaust assembly 110 may operate in a mechanical manner, anelectrical manner, an electromagnetic manner, or combinations thereof.For example, the exhaust assembly 110 may include a valve, a motor, abelt, and a ball screw (the aforementioned elements will be described indetail in FIG. 6). The valve is connected to the ball screw, and thebelt is connected to the motor and the ball screw. The motor iselectrically connected to the controller C of FIG. 3A. In someembodiments, the motor can be controlled by the controller C (i.e., inan electrical manner), and the valve can open, close, or partially openthe opening O of exhaust pipe 122 through the motor, the belt, and theball screw (i.e., in a mechanical manner). In alternative embodiments,the exhaust assembly 110 may include a valve to change the area of theopening O of exhaust pipe 122 using electromagnets (i.e., in anelectromagnetic manner).

Reference is made to FIG. 3A. In some embodiments, the semiconductorapparatus 120 is an electrochemical plating (ECP) apparatus, whichincludes electroplating cells 126 a, 126 b, and 126 c, a filtration andpumping device 121, a dosing device 123, and a chemical dilution module(CDM) 125. The tank 124 is a central bath of the ECP apparatus 120.Electrolyte pipes P1 and P2 connect the tank 124 and the electroplatingcells 126 a, 126 b, and 126 c. The tank 124 is configured to provide theelectrolyte S to the electroplating cells 126 a, 126 b, and 126 cthrough the electrolyte pipes P1, and to recycle the used electrolyte Sfrom the electroplating cells 126 a, 126 b, and 126 c to the tank 124through the electrolyte pipes P2. The tank 124 is an atmosphere tank,which is disposed in a portion of the ECP apparatus 120 that isdifferent from portions where the electroplating cells 126 a, 126 b, and126 c are. The electroplating cells 126 a, 126 b, and 126 c areconfigured to electrofill metal (e.g., copper) on semiconductorsubstrates (e.g., silicon wafers W). The dosing device 123 is configuredto store and deliver chemical additives for the electrolyte S. The tank124 is configured to hold the electrolyte S used as an electroplatingsolution in the electroplating cells 126 a, 126 b, and 126 c. Thefiltration and pumping device 121 is configured to filter theelectrolyte S for the tank 124 and to pump the electrolyte S to theelectroplating cells 126 a, 126 b, and 126 c. The chemical dilutionmodule 125 may store and mix chemicals to be an acid used in functionalmodules 127 a, 127 b, and 127 c for edge bevel removal (EBR) andcleaning surfaces of wafers W.

FIG. 3B is a schematic view of a wafer W in the electroplating cell 126a of FIG. 3A during an ECP process. The other electroplating cells 126 band 126 c of FIG. 3A are similar to the electroplating cell 126 a ofFIG. 3B. The electrolyte S in the electroplating cell 126 a is providedby the tank 124 of FIG. 3A. In other words, the electrolyte S in thetank 124 of FIG. 3A is supplied to the electroplating cell 126 a. Oneelectrode (the anode) in the electrolyte S will undergo oxidation andthe other (the cathode) will undergo reduction. In some embodiments, acopper anode CA is the anode, and the wafer W is the cathode. The metalof the copper anode CA will oxidize, going from an oxidation state (inthe solid form) to a positive oxidation state and become an ion. At thewafer W, the metal ion in the electrolyte S will accept one or moreelectrons from the wafer W and the ion's oxidation state is reduced.This forms a solid metal (i.e., copper) that electrodeposits on thewafer W. As a result, the wafer W disposed in the electroplating cell126 a is electroplated to form interconnect features on the wafer W. Thetwo electrodes are electrically connected to a power source PS, allowingfor a flow of electrons that leave the copper anode CA and flow throughthis connection to the ions at the surface of the wafer W (cathode).

Referring to FIG. 3A and FIG. 3C, after the wafer W is electroplated,the wafer W is rinsed by de-ionized (DI) water F. The water F falls intothe electrolyte S after rinsing the wafer W, thereby diluting theelectrolyte S. The diluted electrolyte S is then recycled to the tank124. As a result, after a number of wafers W, the chemical concentration(e.g., copper concentration) in the electrolyte S in the tank 124 willbe decreased.

Reference is made to FIG. 3A. The exhaust assembly 110 is configured toadjustably exhaust the vapor above the electrolyte S in the tank 124 tomaintain the chemical concentration (e.g., copper concentration) in theelectrolyte S. In some embodiments, the chemical concentration (e.g.,copper concentration) in the electrolyte S can be maintained in asuitable range by controlling the exhaust assembly 110, instead ofdumping a fresh electrolyte solution into the tank 124 during preventivemaintenance (PM). Since the chemical concentration (e.g., copperconcentration) in the electrolyte S is maintained in a suitable rangefor the ECP process, the efficiency of filling holes with metal isstable, and voids are not formed in the metal. As a result, electricalproperty of the metal and product yield can be improved.

Moreover, in some embodiments, the semiconductor apparatus 120 mayfurther include the functional modules 127 a, 127 b, and 127 c, whichmay be configured to perform various process operations. For example, insome embodiments, one or more of the functional modules 127 a, 127 b,and 127 c may be spin rinse drying (SRD) modules. In some embodiments,one or more of the functional modules 127 a, 127 b, and 127 c may bepost-electrofill modules (PEMs), each configured to perform a function,such as edge bevel removal (EBR), backside etching, and acid cleaning ofsubstrates after they have been processed by one of the electroplatingcells 126 a, 126 b, and 126 c. In other words, after a wafer W isprocessed, either the module 127 a, the module 127 b, or the module 127c is configured to perform a desired operation, such as an EBR process,backside etching, and acid cleaning, upon the wafer W. Further, one ormore of the modules 127 a, 127 b, and 127 c may be pre-treatmentchambers. The pre-treatment chamber may be a remote plasma chamber or ananneal chamber. Alternatively, a pre-treatment chamber may be includedat another portion of the apparatus, or in a different apparatus. Inaddition, the semiconductor apparatus 120 includes a robot arm 128 andload ports 129. The robot arm 128 is configured to deliver substratesamong the electroplating cells 126 a, 126 b, and 126 c, the functionalmodules 127 a, 127 b, and 127 c, and the load ports 129 in order toperform corresponding operations.

FIG. 4 is a concentration-time relationship chart presented by the FDCserver 160 of FIG. 2. The FDC server 160 (see FIG. 2) determines if themeasured chemical concentration (e.g., copper concentration) is higherthan or lower than a suitable range for the ECP process. For example,the dotted line L1 is a target value (i.e., baseline). In someembodiments, the target value may be in a range from about 2 g/L toabout 70 g/L. When the target value is lower than about 2 g/L, poorfilling efficiency for holes, electrical failures, and low yield may beprone to occur. When the target value is higher than about 70 g/L, voidsin the electroplated metal, poor electrical property, and low yield maybe prone to occur.

The dotted lines L2 and L3 respectively are an alarm lower limit valueand an alarm upper limit value. If the measured chemical concentrationis lower than the alarm lower limit value or higher than the alarm upperlimit value, the FDC server 160 may send alarm information to thesemiconductor apparatus 120 of FIG. 3A to stop further processing. Insome embodiments, the alarm lower limit value may be in a range fromabout 94% to about 98% of the target value. When the alarm lower limitvalue is lower than about 94% of the target value, poor fillingefficiency for holes, electrical property fail, and low yield may beprone to occur. When the alarm upper limit value is higher than about98% of the target value, voids in the electroplated metal, poorelectrical property, and low yield may be prone to occur. In someembodiments, the alarm upper limit value may be in a range from about102% to about 106% of the target value. When the alarm upper limit valueis lower than about 102% of the target value, poor filling efficiencyfor holes, electrical property fail, and low yield may be prone tooccur. When the alarm upper limit value is higher than about 106% of thetarget value, voids in the electroplated metal, poor electricalproperty, and low yield may be prone to occur.

In some embodiments, when the measured chemical concentration is lowerthan a control lower limit value, the exhaust assembly 110 will start toincrease the opening area of the exhaust pipe 122 (see FIG. 3A) todecrease the vapor in the tank 124, thereby increasing the chemicalconcentration in the electrolyte S. On the other hand, when the measuredchemical concentration is higher a control upper limit value, theexhaust assembly 110 will start to decrease the opening area of theexhaust pipe 122, thereby decreasing the chemical concentration in theelectrolyte S. In some embodiments, the control lower limit value may bein a range from about 97% to about 99% of the target value. When thecontrol lower limit value is lower than about 97% of the target value,the chemical concentration in the electrolyte S may decrease to lowerthan the alarm lower limit value. When the control lower limit value ishigher than about 99% of the target value, the chemical concentration inthe electrolyte S may increase to higher than the alarm upper limitvalue. In some embodiments, the control upper limit value may be in arange from about 101% to about 103% of the target value. When thecontrol upper limit value is lower than about 101% of the target value,the chemical concentration in the electrolyte S may decrease to lowerthan the alarm lower limit value. When the control upper limit value ishigher than about 103% of the target value, the chemical concentrationin the electrolyte S may increase to higher than the alarm upper limitvalue.

In some embodiments, evacuating the vapor is performed such that thechemical concentration in the electrolyte S can be sustained in a rangefrom about 97% to about 103% of the target value. If the chemicalconcentration in the electrolyte S is lower than about 97% of the targetvalue, poor filling efficiency for holes, electrical property fail, andlow yield may be prone to occur. If the chemical concentration in theelectrolyte S is higher than about 103% of the target value, voids inthe electroplated metal, poor electrical property, and low yield may beprone to occur.

In some embodiments, a suitable opening area of the exhaust pipe 122(see FIG. 3A) can be obtained by a computation result of the CIM system130 (see FIG. 2) based on the measured chemical concentration. Moreover,a proportional-integral-derivative (PID) algorithm may be used in theCIM system 130 or the FDC server 160 to figure out the desired openingarea of the exhaust pipe 122 through a control loop feedback, such thatthe CIM system 130 can enable the exhaust assembly 110 to linearlyadjust the opening area of the exhaust pipe 122 and the chemicalconcentration in the electrolyte S can be precisely controlled in asuitable range (e.g., from about 97% to about 103% of the target value).

FIG. 5 is a perspective view of the exhaust assembly 110 and the tank124 of FIG. 3A, in which the exhaust assembly 110 is in a closed state.The closed state means the opening O of the exhaust pipe 122 (see FIG.6) is closed by the exhaust assembly 110. The exhaust assembly 110 islocated on the tank 124. The tank 124 contains the electrolyte S and thevapor V therein. The vapor V is above the electrolyte S and is in theupper space of the tank 124 that is not occupied by the electrolyte S.The exhaust assembly 110 may be programmed to control the vapor fluxthrough the exhaust pipe 122 based on the measured chemicalconcentration.

FIG. 6 is a perspective view of the exhaust assembly 110 of FIG. 5. Theexhaust assembly 110 is connected to the tank 124 and includes a valveVa. The exhaust pipe 122 is connected to the tank 124 (see FIG. 5). Thevalve Va is connected to the exhaust pipe 122. In some embodiments, theexhausting parameter value determined by the CIM system 130 of FIG. 2includes an opening degree of the valve Va. The opening degree of thevalve Va is determined based on the measured chemical concentration. Thecontroller C of FIG. 3A is configured to control the opening degree ofthe valve Va based on the exhausting parameter value. In somealternative embodiments, the controller C of FIG. 3A may be configuredto directly determine the exhausting parameter value (e.g. the openingdegree of the valve Va) and use the exhausting parameter value tocontrol the valve Va. The valve Va includes a valve body 113 and a gate112. The valve body 113 is mounted on the tank 124 and is connected tothe exhaust pipe 122. The gate 112 is movably contained in the valvebody 113 and is below the opening O of exhaust pipe 122. Moreover, theexhaust assembly 110 further includes a motor 114 and a ball screw 116,and the ball screw 116 is connected to the gate 112 and the motor 114.The motor 114 is electrically connected to the CIM system 130 of FIG. 2and the semiconductor apparatus 120 of FIG. 3A to receive and sendinformation. When the motor 114 rotates its shaft in a direction, theball screw 116 connected to the motor 114 may rotate at the same time.The gate 112 connected to the ball screw 116 can be moved below theopening O of the exhaust pipe 122 to close, open, or partially open theopening O of exhaust pipe 122 (see FIGS. 6, 8, and 10). In other words,the area of the opening O of exhaust pipe 122 may vary through movingthe gate 112. The position of the gate 112 is controlled based on themeasured chemical concentration. As a result, the exhaust assembly 110can control the vapor flux through the exhaust pipe 122 by controllingthe area of the opening O of the exhaust pipe 122.

Reference is made to FIGS. 5 and 6. When the measured chemicalconcentration is higher than a control upper limit value, the area ofthe opening O of the exhaust pipe 122 can be decreased through movingthe gate 112. In some embodiments, the gate 112 is moved in a directionD1 to decrease the area of the opening O of the exhaust pipe 122. Inother words, the opening degree of the valve Va connected to the exhaustpipe 122 is decreased. In some embodiments, as shown in FIG. 6, the gate112 may be moved to close the opening O of the exhaust pipe 122. As aresult, the vapor V of FIG. 5 may be retained in the tank 124, such thatthe chemical concentration in the electrolyte S is not continuouslyincreased for the reason of solvent evaporation from the electrolyte S.

In some embodiments, the valve body 113 is disposed at an end of theexhaust pipe 122. The end of the exhaust pipe 122 is sleeved by thevalve body 113, and the gate 112 is accommodated by the valve body 113.The valve body 113 has a slit SL, and the gate 122 is movably receivedin the slit SL.

Moreover, the exhaust assembly 110 further includes gear wheels 115 aand 115 b and a belt 118. The gear wheels 115 a and 115 b arerespectively coupled to the shaft of the motor 114 and an end of theball screw 116. The belt 118 is sleeved on the gear wheels 115 a and 115b, such that the ball screw 116 can be rotated by rotation of the shaftof the motor 114. In addition, the exhaust assembly 110 further includesa connector 117 and linear guides 111 a and 111 b. The connector 117 isconnected to a side of the gate 112. Two sides of the connector 117 arerespectively coupled to the linear guides 111 a and 111 b, and one ofthe two sides of the connector 117 is also connected to the ball screw116. In such a configuration, when the ball screw 116 is rotated, theconnector 117 can move along the linear guides 111 a and 111 b to enablethe gate 112 to move into or outward from the opening O of the exhaustpipe 122.

In some embodiments, the opening degree of the valve Va is from about 0%to about 100%. When the opening degree of the valve Va is about 0%,substantially the entire opening O of the exhaust pipe 122 is closed bythe gate 112. When the opening degree of the valve Va is about 100%,substantially no portion of the gate 112 is in the opening O of theexhaust pipe 122. In some embodiments, an inner diameter of the exhaustpipe 122 is in a range from about 2 cm to about 2 m. When the innerdiameter of the exhaust pipe 122 is greater than about 2 m, the cost ofthe exhaust assembly 110 is expensive, and the slit SL is too large toeasily control. When the inner diameter of the exhaust pipe 122 is lessthan about 2 cm, the efficiency of the exhaust assembly 110 is bad andthus the desired effect of controlling the chemical concentration in theelectrolyte S is difficultly achieved.

FIG. 7 is a perspective view of the exhaust assembly 110 and the tank124 of FIG. 3A, in which the exhaust assembly 110 is in an open state.The open state means the opening O of the exhaust pipe 122 (see FIG. 8)is opened by the exhaust assembly 110.

FIG. 8 is a perspective view of the exhaust assembly 110 of FIG. 7. Whenthe measured chemical concentration is lower than a control lower limitvalue, the area of the opening O of the exhaust pipe 122 can beincreased through moving the gate 112. In some embodiments, the gate 112is moved in a direction D2 to increase the area of the opening O of theexhaust pipe 122. In other words, the opening degree of the valve Vaconnected to the exhaust pipe 122 is increased. As shown in FIG. 8, theopening O of the exhaust pipe 122 is opened through moving the gate 112.As a result, the vapor V of FIG. 7 moves into the exhaust pipe 122 in adirection D3 from the tank 124, and the speed of solvent evaporationfrom the electrolyte S is accelerated, such that the chemicalconcentration in the electrolyte S increases. FIG. 8 shows the opening Oof exhaust pipe 122 is completely opened through moving the gate 112 ofthe exhaust assembly 110.

FIG. 9 is a perspective view of the exhaust assembly 110 and the tank124 of FIG. 3A, in which the exhaust assembly 110 is in a partially-openstate. FIG. 10 is a perspective view of the exhaust assembly 110 of FIG.9. When the measured chemical concentration is between the control upperlimit value and the control lower limit value, the exhaust assembly 110is in the partially-open state. In some embodiments, the gate 112 ismoved in a direction D1 or D2 to close or open a portion of the openingO of the exhaust pipe 122. As shown in FIG. 10, the opening O ispartially opened or closed through moving the gate 112. When the exhaustassembly 110 is in the partially-open state, the chemical concentrationin the electrolyte S may mildly increase or decrease. The chemicalconcentration in the electrolyte S can be tuned through adjusting theopening degree of the valve Va.

FIG. 11 is a perspective view of the exhaust assembly 110 and the tank124 in accordance with some embodiments of the present disclosure. Theembodiment in FIG. 11 can be implemented in addition to the embodimentsshown in FIGS. 6-10. In some embodiments, the exhaust assembly 110includes an exhaust source Pu. The exhaust source Pu is connected to theexhaust pipe 122. In some embodiments, the exhausting parameter valuedetermined by the CIM system 130 of FIG. 2 includes a pumping rate ofthe exhaust source Pu. The pumping rate of the exhaust source Pu isdetermined based on the measured chemical concentration. The controllerC of FIG. 3A is configured to control the pumping rate of the exhaustsource Pu based on the exhausting parameter value. In some alternativeembodiments, the controller C of FIG. 3A may be configured to directlydetermine the exhausting parameter value (e.g. the pumping rate of theexhaust source Pu) and use the exhausting parameter value to control theexhaust source Pu.

When the measured chemical concentration is higher than a control upperlimit value, the pumping rate of the exhaust source Pu can be decreasedto retain the vapor in the tank 124. As a result, the chemicalconcentration in the electrolyte S will not be continuously increasedfor the reason of solvent evaporation from the electrolyte S. On theother hand, when the measured chemical concentration is lower than acontrol lower limit value, the pumping rate of the exhaust source Pu canbe increased to increase the rate of piping the vapor out of the tank124 and to lower the pressure in the tank 124. As a result, the rate ofsolvent evaporation from the electrolyte S is accelerated so as toincrease the chemical concentration in the electrolyte S.

In some embodiments, the exhaust assembly 110 controls the vapor fluxthrough the exhaust pipe 122 to be in a range from about 10 m³/hr toabout 5000 m³/hr. If the vapor flux through the exhaust pipe 122 issmaller than about 10 m³/hr, the efficiency of the exhaust assembly 110is bad and thus the desired effect of controlling the chemicalconcentration in the electrolyte S is difficultly achieved. If the vaporflux through the exhaust pipe 122 is greater than about 5000 m³/hr, thechemical concentration in the electrolyte S is difficultly controlled.

In some embodiments, the exhaust assembly is configured to increase ordecrease a vapor flux through the exhaust pipe based on the measuredchemical concentration. When the measured chemical concentration is toolow, the vapor flux through the exhaust pipe is increased to increasethe chemical concentration in the electrolyte. When the measuredchemical concentration is high enough or too high, the vapor fluxthrough the exhaust pipe is decreased to decrease the chemicalconcentration in the electrolyte.

According to some embodiments, a method of controlling chemicalconcentration in electrolyte includes measuring a chemical concentrationin an electrolyte, wherein the electrolyte is contained in a tank; andincreasing a vapor flux through an exhaust pipe connected to the tankwhen the measured chemical concentration is lower than a control lowerlimit value.

According to some embodiments, a method of controlling chemicalconcentration in electrolyte includes electroplating a wafer using anelectrolyte, recycling the electrolyte to a tank, measuring a chemicalconcentration in the electrolyte, determining an exhausting parametervalue based on the measured chemical concentration, and evacuating avapor in the tank using the determined exhausting parameter value.

According to some embodiments, a semiconductor apparatus includes atank, an exhaust assembly, a prober, and a controller. The tank isconfigured to contain an electrolyte. The exhaust assembly is connectedto the tank. The prober is configured to measure a chemicalconcentration in the electrolyte. The controller is configured tocontrol the exhaust assembly based on the measured chemicalconcentration.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method comprising: electroplating, using anelectrolyte, wafers respectively in a plurality of electroplating cells;recycling the electrolyte to a tank that is connected to theelectroplating cells, wherein the tank is external to the electroplatingcells; measuring a chemical concentration in the electrolyte in thetank; controlling, using a valve over a top of the tank, a vapor fluxthrough an exhaust pipe connected to the tank, wherein the valvecomprises a gate below a bottom end of the exhaust pipe, and controllingthe vapor flux through the exhaust pipe comprises: rotating a ball screwconnected to the gate, wherein the ball screw extends along the top ofthe tank; and rotating a shaft of a motor connected to the ball screw,wherein the motor laterally overlaps the ball screw, and the ball screwis between the motor and the exhaust pipe; and increasing the vapor fluxwhen the measured chemical concentration is lower than a control lowerlimit value.
 2. The method of claim 1, further comprising: decreasingthe vapor flux through the exhaust pipe when the measured chemicalconcentration is higher than a control upper limit value.
 3. The methodof claim 2, wherein decreasing the vapor flux through the exhaust pipecomprises: decreasing an opening degree of the valve, wherein the valveis connected to the exhaust pipe.
 4. The method of claim 1, whereinincreasing the vapor flux comprises: increasing an opening degree of thevalve, wherein the valve is connected to the exhaust pipe.
 5. The methodof claim 1, wherein controlling the vapor flux through the exhaust pipecomprises moving the gate along the top of the tank.
 6. The method ofclaim 1, wherein the gate is over and vertically overlaps the top of thetank.
 7. A method comprising: electroplating a wafer using anelectrolyte; rinsing the wafer by spraying water to the wafer through anozzle after electroplating the wafer in such a manner that the waterfalls into the electrolyte after rinsing the wafer; recycling theelectrolyte to a tank connected to an exhaust pipe; measuring a chemicalconcentration in the electrolyte; determining an exhausting parametervalue based on the measured chemical concentration; and evacuating avapor in the tank using the determined exhausting parameter value,comprising: rotating a ball screw connected to a gate below a bottom endof the exhaust pipe, wherein the ball screw extends along a top of thetank; and rotating a shaft of a motor connected to the ball screw,wherein the motor laterally overlaps the ball screw, and the ball screwis between the motor and the exhaust pipe.
 8. The method of claim 7,wherein determining the exhausting parameter value comprises:determining an opening degree of a valve, wherein the valve is connectedto the exhaust pipe, and the exhaust pipe is connected to the tank. 9.The method of claim 7, wherein evacuating the vapor is performed suchthat the chemical concentration is sustained in a range from 97% to 103%of a target value.
 10. A method, comprising: electroplating a waferusing an electrolyte; recycling the electrolyte to a tank connected toan exhaust pipe; measuring a chemical concentration in the electrolyte;determining an opening degree of a valve based on the measured chemicalconcentration, wherein the valve is directly above the electrolyte andcomprises a gate below a bottom end of the exhaust pipe and having abottom surface above and vertically overlapping a top surface of theelectrolyte in the tank; and evacuating a vapor above the electrolyteand in the tank using the determined opening degree of the valve,comprising: rotating a ball screw connected to the gate, wherein theball screw extends along a top of the tank; and rotating a shaft of amotor connected to the ball screw, wherein the motor laterally overlapsthe ball screw, and the ball screw is between the motor and the exhaustpipe.
 11. The method of claim 10, wherein determining the opening degreeof the valve further comprises: when the measured chemical concentrationis lower than a control lower limit value, increasing the opening degreeof the valve.
 12. The method of claim 11, wherein determining theopening degree of the valve further comprises: when the measuredchemical concentration is higher than a control upper limit value,decreasing the opening degree of the valve.
 13. The method of claim 11,further comprising: moving the gate of the valve to reach the determinedopening degree of the valve by the motor and the ball screw connected tothe gate and the motor.
 14. The method of claim 11, wherein evacuatingthe vapor above the electrolyte and in the tank comprises: evacuatingthe vapor from a top of the tank.
 15. The method of claim 10, furthercomprising: after determining the opening degree of the valve, movingthe gate of the valve along a top of the tank to reach the determinedopening degree of the valve.
 16. The method of claim 10, wherein thebottom surface of the gate directly faces the top surface of theelectrolyte in the tank.